The shallow flaw effect and the local approach to cleavage fracture
Book
·
OSTI ID:403284
- Electricite de France, Moret-sur-Loing (France). Dept. Mecanique et Technologie des Composants
The purpose of this paper is to evaluate the capability of local approach (Beremin model developed in the past by Ecole des Mines de Paris) to explain the shallow flaw effect in cleavage fracture, i.e., significantly higher toughness in specimens with short cracks compared to classical specimens with deep cracks. Numerous two-dimensional finite element calculations are performed on several cracked specimens submitted to mechanical or thermal loading. The behavior of different specimens is examined using the Weibull stress {sigma}{sub w} versus stress intensity factor K{sub j} curves. The comparison between different specimens shows significant differences, related to the a/W ratio. For a given level of the applied stress intensity factor, the probability of cleavage fracture evaluated with the Beremin model is higher on specimens containing deeper cracks. That means that, for a same probability of failure, higher fracture toughness must be obtained on specimens with shallow flaws. This comparison is completed by examining the evolution of stress fields and plastic zones at the crack tip during the loading. Significant differences are observed between each specimen. Those differences are well correlated with the a/W ratio. The effect of a/W ratio on the probability of cleavage fracture is underlined. These results can explain the increase of fracture toughness experimentally observed in different laboratories on specimens with shallow flaws. This study is relevant to fracture in reactor pressure vessels.
- OSTI ID:
- 403284
- Report Number(s):
- CONF-960706--; ISBN 0-7918-1771-7
- Country of Publication:
- United States
- Language:
- English
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